Are you waking feeling more tired than when you went to bed? Apart from having dark circles under your eyes, you feel like you need multiple naps to fight daytime fatigue? That’s usually a sign that you don’t sleep through the night, or more precisely, that you don’t get enough deep sleep.
In this post, I want to talk about if adding vitamin D helps you to get more restorative, refreshing sleep – not just more sleep but the type of sleep that recharges you.
First things first – why lack of sleep is almost always linked to stress
Most people think that sleep deprivation comes from not getting to sleep or not staying asleep at night. But did you know that you can even be sleep deprived with 8 to 9 hours of sleep? Yes, you’re sleeping, but you don’t get enough deep sleep or even not any of it!
It’s not a secret that stress is probably one of the main culprits for lack of refreshing sleep. In times we’re experiencing high levels of stress, we are exhausted and struggle to wind down – we feel “wired and tired”. Usually, our sleep returns to normal once the stress is over.
But what happens if the stress never really seems to go away? If you keep on tossing and turning because cortisol, your primary stress hormone, remains elevated? In that case, your cortisol receptors become less sensitive and require more and more cortisol to keep you going until your overworked adrenals can no longer keep up.
Prolonged stress and increased need for cortisol lead to adrenal burnout, and that’s when you experience poor sleep, daytime fatigue, and exhaustion.
The connection between high levels of cortisol and vitamin D deficiency
First off, although referred to as the “stress hormone”, cortisol isn’t bad! On the contrary, it’s essential because it helps the body adjust to the day’s rhythms.
If your cortisol is well-regulated, your levels will peak in the morning around 8 am to get you ready for the day. And then, in the middle of the night, from midnight to 4 am, when you’re asleep, cortisol will reach its lowest levels.
However, if you can’t sleep or feel tired in the morning, your cortisol levels likely remain too high during the night, and the cause for this may be low levels of vitamin D in your body.
Why is vitamin d important for sleep?
Over the past 15 years or so, there’s been much interest in vitamin D, the sunshine hormone said to help with strong bones, prevent various diseases, and even boost weight loss.
However, there is a growing trend in research to link vitamin D levels also to sleep quality. Several studies have shown that low levels of vitamin D in your blood may lead to a higher risk of sleep disturbances and reduced sleep duration. Why is that?
You have vitamin D receptors in many places in the body, including the central nervous system. In fact, you have an exceptionally high distribution of receptors for vitamin D in the brain areas that regulate the sleep-wake cycle, proving a strong association between the ability to get to all stages and cycles of sleep and your vitamin D levels.
In other words, vitamin D allows your body to get into a night of full, restful sleep, including deep sleep that recharges all of your bodily functions.
What causes vitamin d deficiency?
The key to understanding vitamin D deficiency is that you need to understand what vitamin D is. Vitamin D is actually not a vitamin; it’s a steroid hormone that needs to find a receptor to become active in your body. You can see it this way; a hormone without a receptor is like a key that doesn’t belong anywhere and has nothing to do.
Now, vitamin D has its own receptor, called the vitamin D receptor or VDR. However, a specific class of hormones called glucocorticoids is known to decrease vitamin D receptor expression. And the best-known glucocorticoid is cortisol.
High cortisol and low vitamin D are likely to be a two-way street, with increased cortisol depleting your vitamin D and low vitamin D raising your cortisol, and vice versa.
Why do we need to supplement with vitamin D?
Vitamin D is synthesized mainly in the skin; only 10% is derived from dietary sources. The best way to make vitamin D is to spend a little time in the sunshine without sunscreen. But did you know that we spend on average less than 8% of the day outside?
And even if you are outside, in winter, the angle at which sunlight hits the earth prevents sufficient UVB rays from penetrating the atmosphere. So we simply don’t give our skin the opportunity to produce enough vitamin D.
Also, it’s true that foods like fatty fish, cod liver oil, egg yolks from pastured hens, or liver from grass-fed animals contain vitamin D. However, we would need to eat tons of them to get our required daily dose of vitamin D. So obtaining sufficient vitamin D from natural nonfortified food sources alone is also difficult.
Do GMO foods and glyphosate cause vitamin D deficiency?
There might be one more reason why it’s challenging for us to produce sufficient vitamin D naturally, which has to do with sudden mutations in the vitamin D receptors’ genetics. These mutations may lead to the receptors having a hard time absorbing vitamin D. In that case, the normal amounts of vitamin D just won’t go in, and you have to provide your body with an additional supply.
Now the question is, why are we developing these alterations in the receptor? Since vitamin D deficiency trends have been following the introduction of GMO foods and glyphosate, some people see here a connection. However, this has not been fully proven scientifically, and there could be other reasons.
How much vitamin d should I take daily to improve my sleep?
The daily amount of vitamin D that people are often told to take is roughly between 600 to about 800 international units (IU’s). However, that’s the amount determined to prevent rickets. It’s probably not the amount to create the therapeutic effect for many other conditions that interfere with vitamin D absorption, like autoimmune diseases such as M.S., rheumatoid arthritis, or lupus, or fixing your sleep.
In that case, you are probably going to need more. How much that is, varies from person to person and can be determined by a blood test. However, as you can see in the table, tolerable upper intake levels (U.L.) for vitamin D established by the National Academy of Medicine are 4000 IU/d for everyone from 8 years on.
Some people even say that you need much more, like up to 20,000 IU per day to get better sleep. However, others say that high levels of vitamin D can worsen your sleep quality as it may interfere with your body’s melatonin production. So until there is clear guidance, it is probably wise not to overdo it.
Can too much vitamin D be toxic?
One concern is that too much vitamin D may have a toxic effect. Acute toxicity from vitamin D results from very high vitamin D levels in the blood that can lead to hypercalcemia, higher levels of calcium in your blood. So the risk hasn’t to do with vitamin D itself, it has to do with what it does to calcium.
Hypercalcemia symptoms range from mild, such as thirst and polyuria, to severe, including seizures, coma, and even death. However, acute toxicity from vitamin D supplementation is extremely rare.
In an epidemiological project conducted over ten years between 2002 and 2011 with more than 20,000 subjects who had their vitamin D levels measured, only one case of real acute vitamin D toxicity was identified. That person had a vitamin D level of 364 nanograms per milliliter, well above the threshold of 100 nanograms per milliliter above which it’s considered unhealthy.
And this individual had been taking vitamin D supplements of 50,000 units per day for more than three months along with calcium supplements, which obviously would exacerbate his elevated blood calcium levels.
The risk of disease is much higher if your vitamin D levels are too low
I think the important thing to take home is that acute toxicity from vitamin D supplementation is very rare, and it’s reasonably safe to handle even higher doses in the short term. In this review published in the British Journal of Clinical Pharmacology, they say that Vitamin D treatment appears to be safe at doses of up to 10 000 IU per day.
However, there is not enough information about the long-term effects of taking higher doses of vitamin D. That being said, the risk is much greater if your vitamin D level is too low.
So it’s good to be taking a vitamin D supplement if you’re vitamin D deficient (and most of us are!). But keep in mind that more is not necessarily better. The level of vitamin D supplementation that will generally give you a vitamin D level of more than 50 is or at about 4,000 units a day.
So what vitamin D should I take?
My advice is to take vitamin D of 4,000 units a day. If you take a higher dose for a more extended period, it would be reasonable to get your blood checked to ensure that your vitamin D levels don’t shoot through the roof. You should definitely stay away from megadoses like 50,000 units, even if they’re also available without a prescription. If taken daily, they could lead to toxicity.
Also, keep in mind that there are two main types of D. The first is vitamin D3, which is found in animals, including fish, and is produced by the skin when exposed to sunlight.
The second is vitamin D2, which comes from plant foods, including mushrooms. Studies have shown that D3 is more effective, and thus the preferred choice for supplementation.
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